I have had an old Yamaha Saxophone for over thirteen years. It was bought a bit rough to begin with, and after years of use and abuse, it was time to give this reliable instrument some love. I have a munchkin who has been learning to play, so I figured this would make a wonderful gift.

This instructable will show you how to do a chemical oxidation on brass, bronze, or any copper alloy for that matter.

Why do it?
In this case the chemical oxidation (sometimes called patina, redox, or distressing; depending on the application) serves two purposes: Give the sax a unique vibrant look and protect the brass from further erosion. The color I was going for was a charcoal gray to black. I believe I was successful!

Materials
What you will need:

-Saxophone (or whatever brass/copper/metal you wish to use)
-Small Flat head Screwdriver
-Small Philips Screwdriver
-Masking tape
-Fine grit sandpaper (400+)
-Ferric Nitrate
-Sodium Thiosulfate
-Multipurpose household cleaning agent
-Disposable gloves
-Plastic Tub
-Water
-Cardboard
-Black marker
-Disposable coffee cup
-Disposable spoons
-Rust-Oleum Clear Lacquer

Optional, but it will make your life a heck of a lot easier:
-sandblaster

NOTE: if you don't have a sandblaster, you can make one with
-2' tube
-air compressor
-accessory kit
-baking soda

Total cost for materials (not including the sax, compressor, compressor parts and stuff I already had): A little over $80 bucks

Step 1: Step 1

Disassemble the saxophone. Be careful to write down and keep track of everything you take off, especially the screws.

I used masking tape and a black marker to hold and label everything. I didn't lose anything, so I must have done something right!

Step 2: Step 2

I wanted to test the chemical oxidation first to see what results I could expect. I sanded the neck piece, making sure to sand in the same direction. I used P400 Fine Grit to sand the neck piece. I did NOT sand out deeper scratches; the more you remove from the brass, the pitch of the saxophone changes. You can do what you want!

The formula I used was provided from the Science Company. The formula is as follows

Ingredients

    Sodium Thiosulfate... 6.25 gm
    Ferric Nitrate... 50 gm
    Distilled Water... 1 L

Process

I decided not to use 1 liter of water since I was only experimenting. I used 1 cup. So the formula kept the same ratio, just a smaller amount. Also, I don't have a gram scale, so I used a dry weight conversion of grams to teaspoons.

1 liters = 4.22675284 ; for ease of calculations I rounded to 1 liter = 4.25 cups
1 teaspoon = 5 grams
1 table spoon = 15 grams

So I used 1 cup of (tap) water, 1.45 grams of Sodium Thiosulfate, 11.75 grams of Ferric Nitrate

Heat the water to 120-140°F, 50-60°C. I don't have a thermometer, so I estimated. Water boils at 212 °F (100 °C). I heated to the point where I saw the bubbles at the bottom of the pot (slightly steaming).

Now put on your disposable gloves.

Put the water into the disposable cup. Use the disposable teaspoons to add the Sodium Thiosulfate first, let it dissolve, then add the Ferric Nitrate. If you stirred the water with the spoon, DO NOT stick it in the chemicals! You don't want to contaminate the chemicals with a wet spoon.

Immerse the neck piece for 1 minute. When the neck piece is immersed, it changes to a purplish color after about 45 seconds. The color darkens quickly to the desired black in about 1 minute.

Pull the neck piece out and put it in the rinse cup.

I realized I did not have enough liquid to completely submerge the neck piece. I added about a cup to the solution, which diluted it some, but still got the job done in less than a minute. I also had to submerge the neck piece upside down.

As a side note, I also left a little bit of the lacquer on the neck piece in hopes of it reacting to the chemicals. It did not. This made me realize every bit of lacquer had to be removed, otherwise the brass does not react to the oxidation.

Step 3: Step 3

Satisfied with my results, it was time to move on to the horn. I started sanding by hand, but with all the curves, springs, and turns it was deemed impractical. So I built a make shift sand blaster.

A side note: I did try to use industrial strength stripper. I used two different kinds and they both failed to remove any lacquer.

I used a 2 foot hose, added a small hole where I inserted the air compressor. The other end went directly into the baking soda.

I tried sand first, which was a bit too harsh since it left little bumps, and a bit too wet. So I decided to use baking soda which worked beautifully. As a warning, the baking soda gets EVERYWHERE so do it outside.

Once it was sanded, I rinsed it off in warm water and pat dried.

Step 4: Step 4

Prepare the area where you are going to be working. I used a tub from Home Depot.

I made the mistake of not buying enough chemicals for the amount of water I needed, so I diluted the mix. I ended up using a little over 4 liters of water, with only enough chemicals for 2 liters. This simply meant it took longer than the one minute immersion. Actual time was a couple hours!

Heat the water in a pot then pour into the tub. Add the chemicals.

Even with the diluting, I still did not have enough liquid to submerge the saxophone. My solution to this was to tilt the tub and do half at a time.

The positive side of this is the slowly reacting oxidation yielded a beautiful color transition. The color transition was from a bright copper, to purple, to blue, to brown color, to gray, then finally to black. I contemplated pulling it out when it was blue. The pictures don't do it any justice.

Once that side was done, I flipped it and submerged the bell. If you look closely you can see where the mix did not completely cover the sax.

After both sides are complete, rinse the sax with warm water and let air dry. I hung mine upside down over night using a coat hanger.

A final note, since it took much longer to react, I did pull the saxophone out in the middle of the process. I carefully poured the mix back into the pot and warmed again. I threw the pot away once I was done.

Step 5: Step 5

The next morning, I washed the entire saxophone again and rubbed with a soft cloth to remove some residue. The pictures are what they looked like after I washed the sax.

There was a brown stripe on area where the saxophone was not completely submerged. I liked the way this accident looked, so with the scouring side of a sponge I scrubbed the stripe. I then rinsed again.

The next step is to start lacquering the sax. I used the Rust-Oleum spray on clear lacquer. The first coat was tested on the neck piece. Satisfied with the results, I used a ladder and a coat hanger to hang the saxophone to make lacquering easier.

Step 6: Step 6

Once it was hung, lacquering was quite easy. It was pretty cold outside, so I brought the saxophone inside to dry. Then I took it back to the garage to spray again.

After several coats, I hung the horn right side up to make sure I lacquered every inch thoroughly.

Total coats where about 5-7 on both the horn and the neck piece, which used up one can.

Not in any of the pictures are the thumb piece (not the plastic part), screw, and neck screw which where also sanded, dipped, and lacquered.

Step 7: Step 7

Leave the saxophone to dry for the allotted time indicated on the lacquer can (I believe it was 24 hours to completely dry).

Clean keys with water and Multipurpose household cleaning agent. DO NOT get any on the pads, since the cleaning agent may ruin them.

Carefully assemble the saxophone back the way you started. Again I started with the neck piece to see what it looked like.

Step 8: Done!

Once assembled, I played the sax a bit to see if the pitch had changed. I personally did not notice any, and I would like to believe I have an ear for it since I have used this same horn for many many years.

I included a before picture again.